In recent years, numerous systems have been developed for the reproduction of four-channel or multi-channel sound. These approaches include SQ sound (a CBS development), CD4, and four-channel discrete systems among others.
While there has been increasing interest in quadrophonic systems, a major drawback is the cost differential over stereophonic (two channel) sound. A significant portion of this cost increase results from the need for additional system amplifiers. In all of the systems mentioned above, the additional two-channels of sound requires a second stereo amplifier. This doubles the amplifier cost.
In addition to the increased parts costs, the problems of reliability, cost of labor and general complexity of the multi-channel system mitigate against its widespread acceptance. Thus, a technique which can substantially reduce cost and complexity and increase reliability without sacrificing audio quality is most needed in the multi-channel audio market.
It is accordingly an object of the present invention to provide an audio system for the time sharing of an audio amplifier.
It is an additional object of the present invention to provide a system for the conversion of a single monophonic amplifier into a stereo amplifier with only slightly greater cost than the cost of a monophonic amplifier alone
It is another object of the present invention to provide a system for the conversion of a stereo amplifier into a four-channel system for less than the cost of a monophonic amplifier.
It is still another object of the present invention to provide a system for time sharing at least one audio amplifier which allows no noticeable deterioration of the reproduced sound.
It is still a further object of the present invention to provide a system for the switching of the speaker coil of a sound system without introducing extraneous audible sound at the speaker output.
It is still an additional object of the present invention to provide a time-sharing audio reproduction system employing an amplifier output stage which is directly coupled to the speaker coil.
These and other objects, as well as numerous advantages of the present invention will be apparent from the following disclosure.